The formation of a third body layer on a conventional friction material dur
ing braking tests was studied in some detail using TEM. SEM. and X-ray phot
oelectron spectroscopy (XPS) techniques. Plate shaped micro-contact areas r
epresenting a compositional mix of all components of the tribocouple and ex
hibiting a nanocrystalline microstructure were identified after a run-in pe
riod.